The females are roughly the same size and have different colors.
They seemed ok, but where flaring at each other a bit and kind of checking each other out.
I wasn't really worried because it's such a large tank and there are plenty of hiding spots, but I realized that they are purposely going up to each other and kind of swimming around and being a bit aggressive. Most of them aren't looking for hiding places. 2 of them have good hiding places, but the other 3 are fighting.

I was prepared for fighting, but already, halfway through the day one of their tails is half gone, and I don't want it to be completely gone by the end of the day.

I am probably over reacting, but I don't want any of them to die. I am really terrified.
I put lots of leaves on the top as cover for them and at the bottom there are lots of plants to hide in.

I am also scared that I will have to deal with fin rot because their tails are so injured.
Its weird though because when I watch them in the tank, I don't see them biting at eachother.. or even being that aggressive.

I would put some medicine for their tails in but watch them carefully. They will usually nip and fight a little to establish their pecking order but make sure it doesn't get to bad. If it does than you try introducing them again first introducing the least aggressive and ending with the most aggression because now you know their personalitys.